The Principal Investigator, Dr. Abe, has the long-term goal of pursuing independent investigation in the field of lung cell signal transduction. Receipt of a Mentored Clinical Scientist Development Award will facilitate the growth of Dr. Abe's investigative skills and experience by expanding his knowledge of molecular techniques, as outlined in the proposed studies. The learning objectives set out in this proposal, combined with the support of his Mentors, Drs. Marc Hershenson and Marsha Rosner, and the critical environment within the Section of Pulmonary Biology and Critical Care, and Ben May Institute for Cancer Research at the University of Chicago, will foster Dr. Abe's progression to independent lines of investigation into the mechanisms of lung diseases. The Specific Aims in this proposal will extend earlier inquiries by Dr. Abe into extracellular signal-regulated kinase (ERK) "611", a novel mitogen-activated protein kinase present in the lung which includes a Src-homology 3(SH3) binding motif. Three immediate goals are defined: (1) Determine the tissue specificity and developmental regulation of ERK611 expression in the lung. Extracts and sections from mature and fetal rat tissues will be probed using labeled antisense riboprobes (Northern analysis, in situ hybridization) and antibodies raised against the amino- and carboxy-terminal peptide sequences (Western analysis, immunohistochemistry). (2) Determine the activators of ERK611 in a cell culture system, and the substrates phosphorylated by ERK611 in vitro. Cells will be treated with putative activators of ERK611 and ERK611 phosphorylation and also be determined by examining the function of chimeric ERK611 proteins including either the regulatory or substrate domains of ERK2. (3) Determine the binding partners of ERK611. Binding of ERK611 to various SH3-containing proteins will be assessed both in vivo and in vitro. ERK611 mutations will be used to define specific SH3 binding domains. Finally, the yeast two-hybrid system will be used to identify additional binding partners of ERK611. Elucidation of ERK611 function may provide insight into disease processes which involve lung cell proliferation or apotptosis.